Question re root cache

[Karl Auer]

I wrote:
> > We have had several additional entries in our root cache file for many
> > years (I inherited them). I only just got around to wondering what
> > effect (if any) they might have.
> > [...]
> > Sample:
> >
> >    ch.            999999999 IN NS DOMREG.NIC.CH.
> >    DOMREG.NIC.CH. 999999999 IN A  130.59.1.80
> >
> > Why might someone have added such entries and what use are they, if 
> > any? I personally don't think they will ever be referred to...

A kind soul answered as follows (reposted with permission):
> These entries should be removed. They must have been put there 
> by someone who either did not properly understand how the DNS works or 
> else was on mind-altering substances. :-) My guess is one of your 
> predecessors attempted to pre-load the cache in the (false) hope it 
> would "speed up" resolution of names in .ch.  BIND doesn't work like that. The 
> info in the root.cache file only gets used for a priming query when the 
> name server starts. It makes a query to one of the servers listed in 
> that file to get details of the root zone -- names and addresses of its 
> servers -- which then gets installed in its cache. That act essentially 
> nukes whatever DNS data had been fed to named through the root.cache 
> file.
> 
> I think it was possible in the early days of BIND4 to put info into the 
> server's cache by sticking it in the root.cache file. So this setup 
> you have could have been in place for a long time. People 
> don't like to tinker with "working" DNS setups in case the sky falls 
> in. The error is largely harmless, though I'd suggest you 
> fix it to avoid more confusion and puzzlement for your successors if 
> this folklore was allowed to continue.
> 
> BIND9 will complain about this sort of thing. It will only allow NS and 
> A (and AAAA?) records for "." in the root.cache file. BIND8 might 
> tolerate root.cache files that are broken like you've described. though 
> I suspect it should have had that bug fixed by now. IIRC, BIND[89] 
> keeps the root.cache stuff in a separate data structure from the real 
> cache because it contains special case data that shouldn't be allowed 
> to expire.

Regards, K.
 
--
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Karl Auer (kauer at biplane.com.au)                   +41-43-2660706 (h)
http://www.biplane.com.au/~kauer/                  +41- 1-6327531 (w)